Among the birds you might spot in Greenwich during the Great Backyard Bird Count is the Snowy Owl. Ted Gilman says a food shortage in northern Canada may be causing the owls to forage further south - and intoAmong the birds you might spot in Greenwich during the Great Backyard Bird Count is the Snowy Owl. Ted Gilman says a food shortage in northern Canada may be causing the owls to forage further south - and into the Greenwich area.

With a little luck, it could be a winter that birders mark in their journals with a star.

Lemming populations are crashing in the Arctic tundra, while seed crops are abundant in Connecticut, meaning that snowy owls and winter finches are likely to be seen here in unusual numbers.

“I’ve heard rumors of this happening,” said Angela Dimmett of New Milford, leader of innumerable bird walks in the Northwest Corner. “Word spreads.”

“If there’s an unusual bird around, we hear about it,” said Margaret Robbins, owner of the Wild Bird Unlimited shop in Brookfield.

There’s a whole family of birds, loosely called winter finches, that sometimes arrive in what ornithologists call irruptions. When food sources fail in one place, the birds fly off, in big flocks, to places where the larder is full.

One of those finches — the red crossbill — has already moved from its normal wintering grounds in Alaska and western Canada eastward into the U.S., and in huge numbers.

Birders have already seen red crossbills in one town in the Farmington Valley.

Red crossbills are described nicely by their name. The males are mostly red with darker wings, the females, olive-yellow.

What sets them apart from other finches — like the house finch, which breeds here and shows up every year at backyard feeders — is that the ends of their bills cross to form a sharp little V at the end. Those bills make them expert at tearing apart pine cones.

“They use them to pry the cones open, like a wrench,” Comins said.

There’s also a chance that the red crossbills’ cousins — the white-winged crossbills — will show up in the state. Like red crossbills, they’re cone-eaters, but with a prominent white patch on their wings.

“The first year I started working here, there was a big flock of white-winged crossbills here,” said Ken Elkins, the director of educational programs at the Audubon Connecticut’s Bent of the River nature center in Southbury.

What improves the chances of both crossbills showing up here is that it’s a really good year for evergreen cone crops.

Thomas Philbrick, professor of biology at Western Connecticut State University in Danbury, said many fruit-bearing trees, including those that bear nuts and cones, have an occasional big year as part of their survival strategies.

The strategy is this, Philbrick said: The trees produce average or smaller-than-average crops for a few years in a row, creating a sort of equilibrium between the tree and the creatures that depend on it for food.

Crossbills hang out in evergreens. Unless you have hemlocks or white pines in your yard, you have to travel to see them.

But common redpolls — another winter finch that shows up in the state irregularly — can be feeder birds. They’re small, streaked sparrow-like birds with a bright red cap that stands out in the snow. Comins said it may be a good year for them as well.

The grandest of the winter arrivals are snowy owls. A few show up in the state every year, usually along the coast or in big open fields. This year there may be more than a few; there may be a major irruption happening.

Snowy owls live and breed in the Canadian tundra above the Arctic Circle and depend on lemmings for food. If the lemming population explodes, as it periodically does, well-fed snowy owls have lots of babies and there are a lot of snowy owls. The excess population pushes south in winter.

Because they’re such beautiful birds, people rush to see them and end up harassing them. The owls fly off and get injured.

Robbins said if it’s a good snowy owl year, people have to adapt, bring binoculars, and keep their distance.